1. Mouth breathing: the air flow over the oral mucosa (cheeks, tongue) dries it out, causing a dry mouth.
2. Stress: while in stress, our body secretes less saliva than usual.
3. Many medications (over a thousand!): If your bad breath started after taking certain medication, it might be wise to consult with your physician about it, and maybe have him change the medication accordingly (if possible).
4. Insufficient water uptake: when you don't drink enough, your body secretes less saliva.
5. Too much talking: this is a particular problem for teachers and professors who like to talk and don't always worry about the consequences.
6. Alcohol, smoking and (perhaps) coffee.

Some ways to increase saliva flow are:

• Taking small snacks of healthy foods during the day
• Applying a few drops of lemon to the tongue
• Chewing sugarless gum for up to five minutes
• Yoga teaches another way to get the saliva flowing. Roll your tongue from the sides to the center and breathe in very quickly through your mouth.
• Thinking of a delicious food you'd like to be eating